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1. For measured objects with a normal temperature range below 300°C, use thermal resistors.

2. For measured objects with a normal temperature range above 300°C, use K-type assembled thermocouples.

II. Installation and Maintenance Training for K-Type Assembled Thermocouples and Thermal Resistors

Master the installation methods of K-type assembled thermocouples and thermal resistors;

Learn to use K-type assembled thermocouples and thermal resistors for temperature measurement;

Master the wiring of K-type assembled thermocouples and thermal resistors with secondary instruments.

III. Installation Requirements for K-Type Assembled Thermocouples and Thermal Resistors

For the installation of thermal resistors and K-type assembled thermocouples, attention should be paid to ensuring accurate temperature measurement, safety, reliability, and ease of maintenance, without affecting equipment operation and production processes. The following requirements must be met. When selecting the installation location and insertion depth for K-type assembled thermocouples and thermal resistors, note the following two points:

1. K-type assembled thermocouples and thermal resistors with protective sleeves have heat transfer and heat dissipation losses. To reduce measurement errors, K-type assembled thermocouples and thermal resistors should have sufficient insertion depth:

(1) When the insertion depth of the measuring element exceeds 1m, it should be installed vertically as much as possible, or a support frame and protective sleeve should be added.

(2) If measuring the temperature of flue gas in a flue, even if the flue diameter is 1000mm, an insertion depth of 500mm for the K-type assembled thermocouple or thermal resistor is sufficient.

(3) For K-type assembled thermocouples measuring the temperature of fluid at the center of a pipe, the measuring end should generally be inserted to the center of the pipe (vertical or inclined installation). If the pipe diameter of the measured fluid is 100mm, the insertion depth of the K-type assembled thermocouple or thermal resistor should be selected as 50~100mm (considering the size of the mounting base or flange).

(4) For temperature measurement of high-temperature, high-pressure, and high-speed fluids (such as main steam temperature), to reduce the resistance of the protective sleeve to the fluid and prevent the protective sleeve from breaking under fluid action, a shallow insertion method or a thermal sleeve-type K-type assembled thermocouple can be used. For shallow-insertion K-type assembled thermocouple protective sleeves, the insertion depth into the main steam pipe should be no less than 75mm; the standard insertion depth for thermal sleeve-type K-type assembled thermocouples is 100mm.

2. To ensure sufficient heat exchange between the measuring end of the K-type assembled thermocouple or thermal resistor and the measured medium, a reasonable measurement point should be selected, avoiding installation near valves, elbows, and dead corners of pipes and equipment.

IV. Installation Methods for K-Type Assembled Thermocouples and Thermal Resistors

1. First, measure the dimensions of the flange or thread of the K-type assembled thermocouple or thermal resistor, and process the matching flange or thread base.

2. According to the dimensions of the flange or thread base, make an opening on the pipe to be measured.

3. Weld the flange or thread base. Insert the flange base or thread base into the opening and weld it to the pipe to be measured.

4. Secure the K-type assembled thermocouple or thermal resistor with bolts or screw it into the welded thread base.

5. According to the wiring diagram, connect the junction box of the K-type assembled thermocouple or thermal resistor and connect it to the corresponding display instrument on the panel. Note that the junction box should not contact the pipe wall of the measured medium, ensuring the temperature inside the junction box does not exceed 100°C. The outlet hole of the junction box should be protected against short circuits caused by poor sealing, accumulation of moisture, dust, etc.

6. The installation location of the K-type assembled thermocouple or thermal resistor should consider ease of maintenance and inspection.